"Exposure" in Top Tab bar CS6 shows as Opacity only

[sandpiper]

When I open brushes in CS6 the opacity setting in the top task bar stays fixed. Cannot get it to go to Exposure. The brushes box opens ok and when Transfer and Smooth boxes are ticked, I cannot see the greyed out "Opacity Jitter" settings which allow Pen Pressure in the Control selection box to be seleected. (below Exposure Jitter slider.) This page of settings is unavailable. All I am able to see are the Brush Presets. Can you please advise me how to display the page to adjust Pen Pressure when using Wacom Tablet.
Update to first question. I have found that if I select The Dodge / Burn tools I can get Exposure to show on the top Tab bar. I still cannot get the Pen Pressure selection box to show. ( See Colins DVD tut CS6 number 40)